They don't like to be blinded by their white-background screens while using them in the dark.

I think OP was referring to the sudden obsession with dark mode (in the past year or so). It's not like screens and night time are new things, so what changed in the past while to induce this dark mode craze?

I think it correlates with the "blue light" studies that were released lately. As far as I know they weren't conclusive, but both Microsoft and Apple implemented Flux-like screen dimming, dark mode seems like a logical step.

Personally I prefer light themes, I just turn the lights on so that I don't sit in the dark.

Exactly. Seems all of a sudden every app is releasing their dark mode that they claim “everyone has been long waiting for”.

Oh, that's simple. Because Apple did it.

Dark mode is meant to be used in low light environment.

It's a way to keep people up at night to show them more ads more frequently.

People who aren't insane and who sleep at night have a good lighting in their environment and a light theme.

Sundown here is 16:30. Do you think I can tell my employer that I need to go to sleep after?

Ever heard of artificial light?